The invention relates to a heddle of the kind that can be used in particular as a weaving heddle in power looms.
From European Patent Disclosure EP 0874930 B1, a heddle shaft is known, between whose upper and lower crossbeams heddles are fastened. The heddles are kept stationary, spaced apart and parallel to one another. On both ends, they have one end eyelet each, which wraps around a heddle-holding profile section and is thus held by positive engagement. Moreover, each heddle has an eyelet, through which a yarn passes, such as a warp yarn of a power loom. In operation, the heddle shaft is moved back and forth with the heddles in the longitudinal direction of the heddles, and very high accelerations occur. Attempts have therefore been made to firmly clamp the heddles in such a way that the end eyelets have only little play, or none, at the associated profile section. To that end, it has been proposed that an expandable element be disposed on the heddle support profile section, in the form of a hose that can be subjected to fluid and penetrates the end eyelets parallel to the heddle support profile section and clamps firmly in the expanded state.
With this provision, the end eyelets can be fixed without play on the heddle shaft. However, this requires major effort and expense. In particular, the heddle shaft must be set up for this provision, and provisions must be made for securely and tightly enclosing the actuating fluid.
The play-free fixation of the heddles on the heddle shaft opens up the possibility, even at high operating speed and thus at major accelerations of the heddle shaft, of achieving a secure, controlled mode of operation. The effort and expense this involves, as in EP 0874930 B1, however, is relatively high.
From German Patent Disclosure DE 195 48 176, a heddle for a heddle shaft is known, the shape of whose end eyelets is adapted to the heddle support rail; one end eyelet surrounds the heddle support rail without play, and the opposite end eyelet of the heddle surrounds its associated heddle support rail with a play that is adapted to the maximum sagging of the heddle support rail.
Sagging of the heddle support rails is dependent primarily on the power levels of the power looms and increases if these power levels increase. It is thus extremely difficult for the sagging, which definitively determines the play of an end eyelet of the heddle of DE 195 48 176, in advance. Very often, this play can be ascertained, if at all, only in operation of the power loom.
From German Patent Disclosure DE 10035886 and British Patent 1959, a heddle for a heddle shaft is known that has an elastic connecting means between the heddle and its end eyelet. As a result, the heddle becomes more elastic, and subsequently suspending the heddle from the heddle support rail and replacing heddles in the heddle support rail are easier. However, forces of acceleration and braking must be transmitted from the end eyelet to the heddle via the elastic connecting means.
A heddle is also known from German Patent Disclosure DE 29 35 504, with a heddle shaft and with end eyelets that each fit on one end over a respective heddle support rail. The spacing of the inner bearing faces of the end eyelets from one another is greater than the spacing of the two outer edges of the two heddle support rails, so that the heddles are seated with play on the heddle support rails. To compensate for this play, a compression spring is disposed on one end eyelet; it is braced by one end on the end eyelet and by its other end on the heddle support rail. As a result, the compression spring tenses the opposite end eyelet against the heddle support rail.
The known heddles with separate spring elements require considerable production and manufacturing effort and expense. Moreover, their assembly requires not inconsiderable effort.
With this as the point of departure, it is the object of the invention to disclose a simple provision with which the upper limit for the operating speed of a power loom, which limit originates in the heddle shaft, can be increased still further.